The generation of unidirectional propelling forces by permanent magnets is already known and recognized in U.S. Pat. Nos. 4,151,431 and 4,877,983 to Johnson, and U.S. Pat. No. 4,215,330 to Hartmen, by way of example. According to applicant's first patent (U.S. Pat. No. 4,151,431), such forces are generated by magnetic interaction between a curved magnet bar of an armature guided for movement along a circular path and an arrangement of spaced stator magnets having pole faces of one polarity facing the armature on one side thereof parallel to the path of movement.
According to applicant's second patent (U.S. Pat. No. 4,877,983), the armature magnet is mounted on a vehicle and guided along a path through a magnetic flux zone limited on opposite sides of the path by an arrangement of magnetic pole surfaces of one polarity on stator magnets. According to one embodiment of the second patent, the flux zone is formed by spaced gate assemblies of magnets having exposed pole faces of one polarity in a plane perpendicular to the armature path from which a magnetic field extends to the opposite pole faces and a ring magnet fixed to such opposite pole faces of the other polarity, with a radially inner pole surface of the same polarity producing a magnetic field perpendicular to the first mentioned field to their opposite radially outer pole surfaces. Several other embodiments are illustrated including variations in the armature structure and in the stator structure; however, all of the embodiments teach use of an annular stator assembly.